Merocyanine dyes containing a chain pyrryl group



United States Patent "ice 2,719,151

Patented Sept. 27, 1955 ethyl, carbethqxymethyl, l3-carbethoxyethyl, fi-sulfoethyl, 2 7 151 phenylmercaptomethyl, phenoxymethyl, Q phenylmerr a hyl. fl-p en xy y etc pec a alky roup MERQCYANINE Y s CONTAINING CHAIN nta ngo l to 5. c bon a ms) R epr e a ,GRQUP hydrogen atom, an alkyl group, such as methyl, ethyl, etc.,

or an aryl group, such as phenyl, etc., R3 represents a Donald W. Heseltme and Leslie G. S. Brooker Rochester a .N, Y., assi ors to Eastman Kodak Comp any, Roch hydroiggn 1 91 g g. vsulch l ga a 2 ethyl S n-N- Y-, a o porati n o N w Jersey propy P to Y 0 3 Qr y u 91 as nyl. 2- and p tol l. c and No Drawing. Application December 1, 1953, Re and R together represent the non-metallic atoms Serial 0 necessary to complete a heterocyclic nucleus of the pyri- 11 aaims (CLZWTMOJ) dine series, Z and Z1 each represents the non-metallic atoms necessary to complete a 'heterocyclic nucleus I taining from 5 to 6 atoms in the heterocyclic ring, such as This invention relates to polymethi e dyes and more those Selected from the group consisting of those ,of the particularly to trinuclear polymethine dyes containing a thiazole series (e. g. thia' ole,- 4-methylthiaz ole, S-rnethylpyrryl, indolyl, or pyrrocolyl nucleus, The dyes of our ihllamle, -ph y iaaol -P lY 5-dit thy1- invention can be more accurately described as polythiazole, 4-(2-thieny l)thiazole, etc those of the be g'omethine dyes containing a pyrryl, indolyl, or pyrrocolyl b 'g i b i i 4 o zothiazo e nucleus substituted on the polymethine bridge or inter- 5-chlorobenzothiaiole, 6-ch lorobenzothiazole, 7-chl9 rocyclic chain. benzothia'zole, 4-methylbenzpthiazole, S-methylbengothi: This application is a continuation-in-part of our appliazole, 6-methylhenzothiazole, S-brprnobenzothiazole, 6? cation Serial No. 267,928, filed January 23, 1952, now brpmobenzothiazole, 4-phenylbenzothiazole, 5 -phenyl- U. S. Patent 2,666,761, issued January 19, 1 954. benzothiazole, 4-methogrybenlzothiaaole, 5-methoxybengo- Polymethine dyes containing a pyrryl, indolyl, or thiazoie, 6-rn ethogtyhengo thiazole, 5-iodobenzothiaz ol f pyrrocolyl nucleus have long been known, although such iodobenzgthiazole, 4-ethoxybengothiaaole, 5-ethoxybenz odyes have not, in general, been found to be especially thiazole, tetrahydroben zothiazple, 5,6-dimethoxybenzo: useful in sensitizing photographic silver halide emulsions. thiagole, 5,6 dioayrnethylenebengothiazole, S-hydroxy- Such prior art dyes have been used to advantage in photobepzpthiazole, 6-hygirogrybenzothiazole, etc.), those of the graphic elements aslight-filtering agents, however. naphthothiazole series (e. g. a-naphthothiazole, ti-naph- We have now found a new class of trinuclear dyes conthothiagole, 5-rnethoigy-fi-naphthothiazole, 5 rethoggy-fltaining a pyrryl, indolyl, or pyrrocolyl nucleus which are naphthothiazole, 7- methogry -naphthothiazole, g-rnethespecially useful in sensitizing photographic silver halide oxy 0c n aphthothiazole, etc,), those pf the thionaphemulsions. theno-'7 ,6,4,5- thiazole series (e. g. 4-methoxythionaph- It is, therefore, an object of our invention to provide a eno-7,6,4,5-thiazole, etc.'), those' 01; the oxazole series new class of trinuclear dyes containing a pyrryl, indolyl, (e, g. 4-methylorgazole, 5-methyloxazole, 4-phenylox az ole, or pyrrocolyl nucleus. Another object is to provide meth- 4,5 diphenyloxazole, 4 -ethyloxazole, 4,5-diinethylograzole, ods of making such dyes. Still another object is to pro- S-phenyloxazole, etc), those of the benzoxazole series 'vide photographic silver halide emulsions sensitized with e. g. benzoigazole, j-chlorpbenzoxazole, S-phenylbenzour new dyes. Anotherobject is to provide a method of 40 ogr az ole, '5-methylbenzograzole, 6-methylbenzoxazo1p, 5,6- preparing such emulsions. A further object is to provide dimethylbenzograzole, 4, 6-dimethylbenz oxazole, S-metha new class of intermediates which are useful in preparing onybenzoxagole, 6 methoxybenz oxazole, 5 ethpxybenzour new dyes. Other objects will become apparent from a oxazole, 6-chloroben zo xazole, S-hydroxjtbenzoxazble, 6- consideration of the following description and examples. hydrqxybenzpxazole, etc.) those of the naphthqxazole According to our [invention we provide new trinucjlear series Xe. g. t-naphthoxazole, ,B-naphthoxazole, etc), dyes containing a .pyrryl, indolyl, .or pyrrocolyl nucleus those of thefselenazole series (e. g. 4-rnethylselenazole, 4- l d f flj e t d b th f llowi g ge eral p'henylselenazole, etc. those of the benzoselenazole se formulas: ries (e. g. benzo selenazole, j-chlorobenzoselenazole, 5,-

IZ Z1 where R and R; each represents an alkyl group (i. e. an alm th x nzo e snazol vdwaybems l az l e H Rs t h dro osele zqle e c), th e of t a ha els 0=CH-0(=CH0H) =6 CF we seri s (a a a-n hthos l nazo fiap t o sl m azo e et -l t cs pf the ia o c eries .t azo inq tx 4-.meth lth am ne eta), thos of th -qui l ne se ies 9 (e. -g. quinoline, 3rmethylquinoline, 5-rnethy1 quinoline, 7.- ,N" inethylquinoline, ,8.-r net-hylquino line, 6t chloroquinoline, ,8- chloroquine line, 6-methoxyquinoline, 6 -etho ryquinoline,

vd 0 yq Q .-in i ydr xy u c i jc, e se of -co'hol radical), ,e. g. methyl, ethyl, n-propyl, 'isobutyl, nthe a-qu l e i u 0l n fi me o vqmn 'butyl, is amyl, n-amyl, fi-hydroxyethyl, y-"h-ydroxypropyl, }y q thylquIuOhne, etc), thoseof fi-methoxyethyl, fl-eth-oxyethyl, allyl, fl-rnet-hylallyl, benzyl the l-lsoquinoh-ne series (e. g. isoqumoline, '3,4-d1hydro- '(phenylmethyl), fl-pheny'lethyl, -B-carboxyethyl, carboxy isoquinoline, etc), those-of the S-iSoquinoline series (e. g.

"methyl, a-carboxyethyl, 'y-carboxypropyl, fi-acetoxyethyl, isoquinoline, etc.'), those of the 3,3-dialkylindolenine secetoxypropy1, carbomethoxymethyl, fi-carbomethoxyries (e. g. 3,3-dimethy-lindolenine, 3,3,5-trimethylindole nine, 3,3,7-trimethylindolenine, etc.), those of the 2- pyridine series (e. g. pyridine, 3-methylpyridine, 4-methyl- Pyridine, 5-methylpyridine, 6-methylpyridine, 3,4 dimethylpyridine, 3,5-dimethylpyridine, 3,6-dimethylpyridine, 4,5-dimethylpyridine, 4,6 -dimethylpyridine, 4- chloropyridine, S-chloropyridine, 6-chloropyridine, 3- hydroxypyridine, 4-hydroxypyridine, S-hydroxypyridine, 6-hydroxypyridine, S-phenylpyridine, 4-phenylpyridine, 6- phenylpyridine, etc.), those of the 4-pyridine series (e. g. 2-methylpyridine, 3-methylpyridine, 2-chloropyridine, 3- chloropyridine, 2,3-dimethylpyridine, 2,5-dimethylpyridine, 2,6-dimethylpyridine, Z-hydroxypyridine, 3-hydroxypyridine, etc.), etc. Z2 represents the non-metallic atoms necessary to complete a pyrrole nucleus (includes simple pyrrole nuclei and condensed nuclei, e. g. indole), X represents an acid radical, e. g. chloride, bromide, iodide, thiocyanate, sulfamate, methylsulfate, ethylsulfate, perchlorate, benzenesulfonate, p-toluenesulfonate, xylenesulfonate, etc., L represents a methine group (substituted or unsubstituted, e. g. =CH, =CCH3, etc.), n and d each represents a positive integer of from 1 to 2, m and q each represents a positive integer of from 1 to 3, and Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, such as those selected from the group consisting of those of the thiazolone series, for example: those of the 2,4(3,5)-thiazoledione series, such as 2,4(3,5)-thiazoledione, 3 alkyl-2,4( 3,5 thiazolediones (e. g. 3-ethyl-2,4(3,-,S)-thiazoledione, etc.), 3-pheny1- 2,4( 3,5 thiazoledione, 3-a-naphthyl-2,4(3,5) thiazoledione, etc., those of the 2-thio-2,4(3,5)-thiazoledione (rhodanine) series, such as 3-alkyl-2-thio-2,4(3,5)- thiazolediones (3-alkylrhodanines) (e. g. 3-ethyl-2-thio- 2,4(3,5)-thiazoledione (or 3-ethylrhodanine), 3-phenyl-2- thio-2,4(3,5)-thiazoledione (3-phenylrhodanine), S-a-naphthyl-2-thio-2,4(3,5)-thiazoledione (3-a-naphthylrhodanine), 3 l -benzothiazyl)-2-thio-2,4(3 ,5 )-thiazoledi0ne (2-(1 -benzothiazvDrhodanine), etc., those of the 2-alkylmercapto- 4(5)-thiazolone series, such as 2 ethvlmercapto 4(5) thiazolone, etc., those of the thiazolidone series, such as 4-thiazolidone or its 3-alkvl (e. g. ethyl, etc.), 3-phenyl or S-a-naphthyl derivatives, those of the 2-alkylphenylamino-4(5)-thiazolone series (e. g. 2-ethylphenylamino-4(5)- thiazolone, etc.), those of the 2-diphenylamino-4(5)-thiazolone series; those of the oxazolone series, for example: those of the 2-thio-2,4(3,5)-oxazoledione series, such as 3- alkvl-2-thio-2,4(3,5)-oxazolediones (e. g. 3-ethyl-2-thio- 2,4(3,5)-oxazoledione, etc.), those of the 2-imino-2,4(3,5)- oxazolone (pseudohydantoin) series, etc.; those of the imidazolone series, for example: those of the 2,4(3,5)- imidazoledione series, such as 2,4(3,5)-imidazoledione (hydantoin) or its 3-alkyl (e. g. ethyl, etc.), 3-phenyl or 3-a-naphthyl derivatives as well as its 1,3-dialkyl (e. g. 1,3-diethyl, etc.), l-alkyl-3-phenyl (e. g.- l-ethyl-3- phenyl, etc.), l-alkyl-3-naphthyl (e. g. l-ethyl-3-anaphthyl, etc.), 1,3-diphenyl, etc. derivatives, those of the 2-thio-2.4(3,5)-imidazoledione series, such as 2-thio- 2,4(3,5)-imidazoledione (2-thiohydantoin) or its 3-alkyl (e. g. 3-ethyl, etc.), 3-phenyl or 3-a-naphthyl derivatives as well as its 1,3-dialkyl (e. g. 1,3-diethyl, etc.), l-alkyl- 3-phenyl (e. g. l-ethyl-S-phenyl, etc.) 1-alkyl-3- naphthyl (e. g. 1-ethyl-3-u-naphthyl), 1,3-diphenyl, etc. derivatives, those of the 2-alkylmercapto-5(4)-imidazolone series, such as 2-n-propylmercapto-5(4)-imidazolone;

those of the thionaphthenone series, such as 2(1)- thionaphthenone or l(2)-thionaphthenone; those of the pyrazolone series, such as pyrazolone or its l-alkyl (e. g. methyl, ethyl, etc.), l-phenyl, l-naphthyl (e. g. 1-mnaphthyl), 3-alkyl (e. g. methyl, ethyl, etc.), 3-phenyl, e-naphthyl (3-a-naphthyl), 1-alkyl-3-phenyl (e. g. 1- methyl-3-phenyl, etc.) 3-alkyl-l-phenyl (e. g. 3-methyll-phenyl, etc.), 1,3-dialkyl (e. g. l,3-dimethyl, etc.), 1,3-diphenyl, etc. derivatives; those of the oxindole series, such as 2,3-dihydro-3-ketoindole, and like five-membered heterocyclic nuclei; those of the 2,4,6-triketohexahydropyrimidine series, for example, 2,4,6-triketohexahydropyrimidine (barbituric acid), 2-thio-2,4,6-triketohexahydropyrimidine (Z-thiobarbituric acid) as well as their l-alkyl (e. g. l-ethyl, etc.) or 1,3-dialkyl (1,3- diethyl, etc.) derivatives; those of the 3,4-dihydro-2(l)- quinolone series, such as 3,4-dihydro-2(1)-quinolone (dihydrocarbostyril); those of the 3,4-dihydro-2(l)- quinoxalone series, such as 3,4-dihydro-2( l)-quinoxalone (oxydihydroquinoxaline), etc.; those of the 3-phenomorpholone (1,4,3 benzoxazine 3(4) one or benzo-fl-morpholone) series, such as 3-phenomorpholone, etc.; those of the 1,4,2-benzothiazine-3 (4)-one (ketodihydrobenzoparathiazine) series, such as ketodihydrobenzoparathiazine, etc., and like six-membered heterocyclic nuclei.

The new dyes of our invention represented by Formula I above can advantageously be prepared by condensing an intermediate selected from those represented by the following general formula:

1'1. wherein R, R2, R3, Z, Z2, X and n each have the values given above, with a cyclammonium quaternary salt selected from those represented by the following general formula:

wherein R1, Z1, and d have the values given above, X1 represents an acid radical, such as those set forth above for X, and Y represents an electro-negative group, such as an alkylmercapto group, an arylmercapto group, e. g.:

wherein R4 represents an alkyl group or an aryl group, such as those given for R3 above; or a p-arylaminovinyl or fi-arylaminobutadienyl group, e. g.:

wherein R5 represents an acyl group, such as acetyl, propionyl, benzoyl, etc. or a hydrogen atom, R6 represents an aryl group, such as phenyl, o-, mand p-tolyl, etc., and e represents a positive integer of from 1 to 2; a halogen atom; etc.

The new dyes of our invention represented by Formula II above can advantageously be prepared by condensing an intermediate selected from those represented by Formula III above with an intermediate selected from those represented by the following general formula: V /,Q\

o=oc=oH(cH=oH 1lTIR1 wherein R7 represents an acyl group, such as acetyl, propionyl, benzoyl, etc., R8 represents an aryl group, such as phenyl, 0-, m-, and p-tolyl, etc., and Q and q have the values given above.

The condensations of the compounds represented by Formula III with either the compounds of Formula IV or the compounds of Formula V can advantageously be accelerated by heating, e. g. at temperatures varying from room temperature (about 20 C.) to C., or to the reflux temperature of the reaction medium. Inert solvents, such as the aliphatic alcohols, e. g. ethanol, n-

.propanol, n-butanol, etc., 1,4-dioxane, pyridine, etc. can

be used. Basic condensing agents can also be employed to advantage. Typical basic condensing agents comprise the trialkylamines (e. g. triethylamine, tri-n-propylamin'e,

tri-n-butylamine, triisoamylarnine, etc.), the N,N-dialkylanilines (e. g. N,N-'dimethylaniline, 'N,Nrdiethylaniline, etc.), N-aikylpiperidines (e. g. 'N-methylpiperidine', N-ethylpiper idine,etc.),etc. I i

The intermediates represented by Formula III can advantageously be prepared by condensing a cyclammonium quaternary salt selected from thoserepresented'by the following general formula: vi V.

VI .z

wherein R, Z, X and n have the values giuexilabovq, together with an alkyl orthoacetate selected from those represented by the following general formula:

VII CHa--'C('OR")3 wherein R" represents an alkyl group, such as methyl, ethyl, etc., and a. compound selected irom those represented .by the following general jormula:

VIII HC\ ii -re ii.

wherein R2, and R3, and Z2 each have the values given 6 10, 1951.) The intermediates of Formulas VI, VII, and VIII have also been previously described in the art. (For example, those of Formula VI in U. 8. Patent 2,537,880, issued January 9, 1951, those of Formula VIII in .British Patent 529,440, accepted November 21, 1940, and those of Formula VII in U. S. Patent 1,944,563, issued March 19, 1935.)

The following examples will serve to illustrate more fully the manner whereby we practice our invention.

he n R, Ra, Re, and X h ve t aa ne l venia o e- The inter-mediates represented by Formula IILabpve are new. Thecondensation ofthe compounds of-Formula itogether with .those of Formulas VI. I .and VIILcan advanatageousl y ,be carried out .in .the presence ,of .an ai filit .d ilu- ,ent, such as ethanol, n-ibutanol, n-propanohiacetic acid,

acetic anhydride, dioxane, .etc. :Carboxylic .anhydrides,

such as acetic anhydride, have been'fonnd to -be particularly useful in increasing the yields of the desired intermediates represented by "Formula FI-II. 'Heating -accelerates the .condensati'ons, .and in .general, temperatures ar ying from room temperature to the reflux temperature rat :the reaction mixture ,have been found to be useful.

The intermediates of Formula IV wherein Y represents a B-arylaminovinyl or fi-arylaminohutadienyl group have been previously described in the art. (See, -.for example, British ,Patent 344,409, accepted March 4, 19,31.) The intermediates of Formula hV wherein Y represents an electro negative group are also Well known. (See, for example, British Patent 42 1,55 9, accepted February 18, 193 5.") The intermediates of Formula V have also been .P SWiQ Sl-l describe n he r (S e, ifo example; Pa .et al. ,Jour. -,Chem.soc,; vol. Cid-( 1909), 13,11 143; M01. 35 (19,13 p. 959,; vol. 5:8 6911162), 11).. 1841,4101; .40 l-91'8:-).,:p. 562; vol. 44 l9 22,),;p. 23,10; Benichte, Mel-. 35 (19.021), .p. .249'6g'and EU. 58. Patent 2,548,571, issued'April vso I-ethyl 2,3',5,6-tetramethyl-3-pyrrolothiacarbocyanine iodide (1.09 grams, 1 mol.) and ?:methyl-2.rneth-y lmercaptobenzothiazolium p toluenesulfonate (03-92 gram, 1 mol.) were dissolved in ethyl alcohol (10 ml.)-,and triethylamine (0.5 ml., 2 mol.) was added. The reaction mixture was heated under reflux -for ten minutes and the crude dye precipitated .bythe addition of water ml.). The crude dye was filtered 01f, dried-and then recrystallized from methyl alcohol; after two ;recrystallizations the yield of pure dye was 0.78 gram (53 percent); melting point 169 170 methyl -thia-' 2-carbocyanine iadide l-ethyl ,2;3,5,6-tetramethyl-3-pyrrolothiacarhocyanine iodide (1.09 grams, 111101;) ,and .hmethyl-Z-phenylrnercaptoquinolinium iodide (0.95 gram, 1 mol.) -.were dissoled in ethyl alcohol (15 ml.,) and triethyglamine (0.7 ml., 2 mol.) was added. The reaction mixture was heated under reflux for 15 minutes, .then chilled overnight, filtered and the crude dye -(9,3 percent) dried. After'two recnystallizations from methyl alcohol the yield of pure dye wa .09.? .gram (68 erce t); m l point 25:0"-

AnagYsi -fiQaIw-M d if :CZQHSDINLISI Bound: 1.2 -1.

amine (0.7 ml., 2 'mol.) wereheated under reflux in ethyl alcohol (1-5-ml.) for 15 minutes.

Example 4.'3,3'-diethyl-9-(l -ethyl-2,5-dimethyl-3- pyrryl) thiaa'icarbocyanine perchlorate lzHs 1,3'-diethyl 2,5,6-trimethyl-3-pyrrolothiacarbocyanine iodide (1.13 grams, 1 mol.), 2-5-acetanilidovinylbenzothiazole ethiodide (1.13 grams, 1 mol.) and triethylamine (0.7 ml., 2 mol.) were refluxed in ethyl alcohol (15 ml.) for 15 minutes. The crude dye was precipitated by the addition of aqueous sodium perchlorate (2 grams in 50 ml.). The crude dye was filtered off, dried and twice recrystallized from methyl alcohol. The yield of pure dye was 0.97 gram (65 percent); melting point 205 206 C.

Example 5. 3 ethyl 5 [4 (3 -ethyl 2(3H) benzothiazolylidene) 3 (I ethyl 2,5 dimethyl 3 pyrryl)butenylidene]rhodanine 1,3 j diethyl 2,5,6; trimethyl 3 pyrrolothiacarbocyanine iodide (0.75 gram, 1 mol.), 5-acetanilidomethyla ene-3-ethylrhodanine (0.55 gram, 1 mol.) and triethylamine (0.5 ml., 2 mol.) were refluxed in ethyl alcohol 15 ml.) for 30 minutes. The crude dye was thrown out of solution by the addition of water (100 m1.), filtered, dried and twice recrystallized from pyridine and methyl alcohol. The yield of pure dye was 0.58 gram (70 percent); melting point 192 193 C.

Example 6. 3,3 dimethyl 9 (2 -phenyl 1 pyrrocolyl) 4,5,4',5' dibenzothiacarbocyanine p toluene sulfonate =CHC N Ca. I

OSO2-CuH CH3(D) 3' methyl 2 phenyl 4',5' benzo 1 pyrrocolothiacarbocyanine p-toluenesulfonate (1.51 grams. 1 mol.), 1 methyl 2 methylmercaptonaphthoE1,2]thiazolium p-toluenesulfonate (1.05 grams, 1 mol.) and triethylamine (1.4 ml. 1 mol. l 300% excess) were refluxed in ethyl alcohol (20 ml.) for twenty minutes. The reaction mixture was chilled, filtered, and the crude dye was washed with ether, water, and acetone, and dried. After two recrystallizations from methyl alcohol, the yield of purified dye was 25%; M. P. 294-S C. dec.

Example 7. -+=3 ethyl 9 (1- ethyl 2,5 dimethyl 3 pyrryl) 3 methyl 4,5,4',5' dibenzothz'acarbocyanine iodide" Example 8. 9 (2,5 dimethyl 1 phenyl 3 pyrryl) 3,3 dimethyl 4,5,4',5 dibenzothiacarbocyanine iodide 2,3',5,6 tetramethyl 1 phenyl 4,5 benzo 3 pyrrolothiacarbocyanine iodide (0.83 gram, 1 mol.) and 1 methyl 2 methylmercaptonaphthoE1,2]thiazolium p-toluenesulfonate (1.04 grams, 1 mol. excess) and triethylamine (1.0 ml., 1 mol. 300% excess) were refluxed in ethyl alcohol 10 ml.) for one hour. The reaction mixture was chilled and filtered and the crude dye washed with water, methyl alcohol, and acetone, and dried. The yield of purified dye after two recrystallizations from methyl alcohol was 53%; M. P. 217-18 C. dec.

Example 9. 3,3 diethyl 9 (3 indolyl) 4,5,4',5' dibenzoselenathiacarbocyanine iodide C N N 4321516 HC 02415 I i 3' ethyl 8 methyl 4,5 benzo 3 indolothiacarbocyanine iodide (0.50 gram, 1 mol.), l-ethyl-Z-ethylmercaptonaphthofl,2]selenazolium ethosulfate (0.90 gram, 1 mol. excess) and triethylamine (0.6 ml., 1 mol. 300% excess) were refluxed in ethyl alcohol (10 ml.) for one hour. The reaction mixture was filtered hot and the product was thoroughly washed with methyl alcohol and dried. The yield of purified dye was 59% after two recrystallizations from cresol and methyl alcohol; M. P 281 2 C. dec.

Example 10. 3,3 dimethyl 9 (2 methyl 3 in- --dolyl) 4,5,4,5 dibenzothiacarbocyanine p toluenesulfonate 2,3',8 trimethyl 4,5 benzo 3 indolothiacarbocyanine p-toluenesulfonate (1.04 grams, 1 mol.), 1- methyl 2 methylmercaptonaphtho[1,2]thiazolium ptoluenesulfonate (1.26 grams, 1 mol. 50% excess) and triethylamine (0.8 gram, 1 mol. 300% excess) were dissolved in ethyl alcohol (15 ml.) and heated under reflux for one hour. The reaction mixture was chilled and filtered and the crude dye was washed with water and acetone and dried. After two' recrystallizations from methyl alcohol, the yield'of purified dye was 42%; M. P.

Example 11. 9 (1,3 dimethyl 2 indolyl) 3,3 diethyl 4,5,4,5' dibenzothiacarbocyanine bromide 3' ethyl 1,3,8 trimethyl 4',5' benzo 2 indolothiacarbocyanine bromide (0.57 gram, 1 mol.), 1- ethyl 2 ethylmercaptonaphthol1,2]thiazolium bromide (0.71 gram, 1 mol. 100% excess) and triethylamine (0.6 ml., 1 mol. 300% excess) were refluxed in ethyl alcohol (10 ml.) for thirty minutes. The reaction mixture was filtered hot and the crude dye thoroughly washedwith methyl alcohol and dried. After two recrystallizations from methyl alcohol, the yield of purified dye was 32%; M. P. 2423 C. dec.

Example 12. 3,3 dimethyl 9 2 methyl 3 indolyl) oxacarbocyanine perchlorate tin. Hie-o H3t. ClO

2,3,8-trimethyl-3-indoloxacarbocyanine iodide (2.15 grams, 1 mol.), 3-methyl-2-methylmercaptobenzoxazolium p-toluenesulfonate (3.4 grams, 1 mol.+100% excess) and triethylamine (1.4 ml., 1 mol.+100% excess) were refluxed in ethyl alcohol (20 ml. for twenty minutes. The reaction mixture was chilled and the dye converted to the perchlorate by the addition of sodium perchlorate (5 grams) in water (100 ml.). The crude dye, after thoroughly washing with water and ether was dissolved in methyl alcohol ml.), again precipitated by the addition of aqueous sodium perchlorate and then stirred until crystalline. The product was then filtered 011 and twice recrystallized from methyl alcohol. The yield of purified dye was 14%; M. P. 1-99200 C. dec.

3-ethyl-8-methyl-3-indolothiacarbocyanine iodide (2.23 grams, 1 mol.), 2-fi-acetanilidovinyl-3-ethylbenzothiazolium iodide (2.25 grams, 1 mol.), and triethylamine (1.4 ml., 2 mols.) were dissolved in ethyl alcohol (20 ml.) and heated under reflux for thirty minutes. The crude dye was thrown out of solution by the addition of sodium iodide (5 grams) in water ml.). The product was twice dissolved in acetone (20 ml.) and precipitated with water (100 ml.) and then dissolved in methyl alcohol 100 ml.) and treated with sodium iodide (5 grams). The solution was filtered, the filtrate chilled for several days and the crystalline product filtered. After two recrystallizations from methyl alcohol, the yield of purified dye was 0.30 gram (20 percent). M. P. 209-10 C. dec.

Example J5.-5'-chl0r0-3,3-diethyl-11-(2-methyl-3- v indolyl) oxathiadicarbocyanine iodide C2115 HaCC I C H5 5' chloro 3' ethyl 2,8 dimethyl 3 -indolothiacarbocyanine p-toluenesulfonate (1.7 6 grams, 1 mol.), 2- t? acetanilidovinyl 3 ethylbenzoxazolium iodide (1.45 grams, 1 mol.), and tr-iethylamine (0.46 ml., 1 mol.) were dissolved in ethyl alcohol (20 ml.) and heated under reflux for thirty minutes. The reaction mixture was cooled and the crude dye thrown out of solution by the addition of water (100ml) The aqueous solution was decanted and the residue dissolved in methyl alcohol (30 ml.), sodium iodide (5 grams) was added and the mixture stirred until crystallization started. The mixture was then chilled overnight, filtered, and the crude dye washed with a little methyl alcohol and dried. After two .recrystallizations from methyl alcohol, the yield of pure dye was 0.38 gram (18 percent). M. P. 198-9 C. dec.

Example 16.--5,5-dichloroe3,3'diethyl-9-(2-methyl-3- indalyl) thiadicarbocyanine iodide water was decanted andthe crude dye dissolved in methyl alcohol (5-0 ml.) and sodium iodide (5 grams) added 3'-ethyl-2,8-dimethyl-3 indolothiacarbocyanine iodide (1.53 grams, 1 mol.), Z-B-acetanilidovinyl-3-ethylbenzothiazolium iodide (1.50 grams, 1 mol.), and triethylamine (0.46 ml., 1 mol.) were dissolved in pyridine and heated under reflux for fifteen minutes. The crude dye was thrown out of solution by the addition (with stirring) of water 100 ml.). The water was decanted and the residue stirred with methyl alcohol (20 m1.) until crystalline. The crude dye was then boiled with methyl alcohol, chilled, filtered, washed with methyl alcohol, and dried.

After two recrystallizations from methyl alcohol, the

yield of pure dye was 1.12 grams (54 percent). M. P.

227-8 C. dec.

Example 18.-[4-(5-chl0r0-3-ethyl 2(3H) benzothiazolylidene) 3 (2 methyl 3 indolyl) 2 butenylidene1-3-ethylrhodanine 5 chloro 3' ethyl 2,8 dimethyl 3-indolothiacarbocyanine p-toluenesulfonate (1.76 grams, 1 mol.), 5- 4 acetanilidomethylene-3-ethylrhodanine (1.02 grams, 1 mol.), and triethylamine (0.46 ml., 1 mol.) were dissolved in pyridine and heated under reflux for thirty minutes. The reaction mixture was chilled and the crude dye thrown out of solution by the addition (with stirring) of water (100 ml.). The aqueous pyridine solution was decanted and the residue stirred with methyl alcohol until crystalline. The mixture was then heated to boiling, chilled, filtered, and the crude dye washed with methyl alcohol and dried. pyridine and methyl alcohol, the yield of purified dye was 0.91 gram (52 percent). M. P. 2868 C. dec.

Example 19. 3-ethyl 5 [4 (3 ethyl 2(3H) benzoxazolylidene) 3 (2 methyl 3 indolyl) 2 Janlenylidenelrhodanine (0.46 ml., 1 mol.) were dissolved in pyridine ml.) and The crude dye 75 heated under reflux for fifteen minutes.

After two recrystallizations from 5 was thrown out of solution by the addition (with stirring) of water ml.). The aqueous portion was decanted and the residue stirred with methyl alcohol until crystalline. The mixture was heated to boiling, chilled, filtered, and the crude dye washed with methyl alcohol and dried. After two recrystallizations from pyridine and methyl alcohol, the yield of pure dye was 0.62 gram (39 percent). M. P. 2434 C. dec.

Example 20.-3 ethyl 5 -[4 (3 ethyl 2(3H) benzothiazolylidene) 3 (2 methyl 3 indolyl) 2 butenylidene] rhodanine il-N-CzHs 3 ethyl 2,8 dimethyl 3 indolothiacarbocyanine iodide (1.53 grams, 1 mol.), S-acetanilidomethylene-3- ethylrhodanine 1.02 grams, 1 mol.), and triethylamine (0.46 ml., 1 mol.) were heated under reflux for fifteen minutes in pyridine (15 ml.). The crude dye was thrown out of solution by the addition (with stirring) of water (100 ml.). The aqueous pyridine solution was decanted and the crude dye alternately stirred and heated with methyl alcohol (50 ml.) until crystallization started. The reaction mixture was then chilled, filtered, and the crude dye washed with methyl alcohol and dried. After two recrystallizations from pyridine and methyl alcohol, the yield of pure dye was 0.72 gram (44 percent). M. P. 218-19 C. dec.

Example 21.3 ethyl 5 [4 (I methyl 2(1H)- naphth0[1,2]thiazolylidene) 3 pyrryl 2 butenylidenelrhodanine 3',6 dimethyl 4,5 benzo 3 pyrrolothiacarbocyanine p-toluenesulfonate (1.59 grams, 1 mol.), S-acetanilidomethylene-3-ethylrhodanine (1.02 grams, 1 mol.), and triethylamine (0.46 ml., 1 mol.) were dissolved in pyridine 20 ml.) and heated under reflux for thirty minutes. The crude dye was precipitated by the addition with stirring of water (100 ml.). The aqueous pyridine was then decanted and the residue stirred with methyl alcohol (50 ml.) until crystallization started. The mixture was then heated to boiling, chilled, filtered, and the crude dye washed with methyl alcohol and dried. After two recrystallizations from pyridine and methyl alcohol, the yield of pure dye was 0.92 gram (58 percent). M. P. 237-8 C. dec.

Example 22.3 ethyl 5 [4 (1 ethyl 2(1H) naphth0[I,2]thiaz0lylidene) 3 (2 methyl 3 ind01yl)- Z-butenylidenelrhodanine 0 S l N-C2Hs C=CH-C=CHCH=C 0=s 3 ethyl 2,8 dimethyl 4',5 benzo 3 indolothiacai'bocyanifie iodide (1.28 grams, 1 mol.), acet'afiilidomethylene-3-ethylrhodanine (0.84 gram, 1 mol. plus percent), and triethylam'ihe (0.7 ml., 1 mol. plus 100 percent) were dissolved in pyridine (10 ml.) and heated under reflux for fifteen minutes. The crude dye was thrown out of solution by the addition with stirring of 50 percent aqueous methyl alcohol "(100 1111.). The crude dye was filtered ofl, washed with water and methyl alcohol and dried. After two recrystauizarions from pyridine and methyl alcohol, the yield of pure dye was 1.09 grams (79 percent). M. P. 274-5 dec.

Example 23.4 t4 l any; {mm m hrharrzt thiazolylidene) 3 [2 methyl 3 indolyl) 2 butenylidene] 3 methyl 1 phen'yl 5 pyrazolone 3" ethyl 2, 8 dimethyl 4',5' benzo 3 indolothiacarb'ocyanine idodide (1.28 grams, 1 mol.), 4-aceta'nilidomethylene 3 methyl 1 phenyl '5 pyra'zolone (0.98 gram, 1 mol. plus 20 percent), and triethylamine (0.7 "ml., 1 mol. plus 100 percent) were dissolved in pyridine 1111,) and heated under reflux for fifteen minutes. The crude 'dye was thrown out of solution by the addition of water (25 ml.). The aqueous solution was decanted and the crude dye boiled with ethyl alcohol (50 ml.) until crystalline. The mixture was then chilled and filtered and crude dye washed with water and methyl alcohol and dried. After two recrystallizations from pyridine and methyl alcohol, the yield ofpure dye was 0.84 gram (59 percent). M. P. 223-5 C. dec.

3' ethyl 2,8 dimethyl 4Z5" benzo 3 indolothiacarbocyan'i'ne iodide (1.28 grams, 1 mol.), 3-ethyl- 1-phenyl-2-thiohydantoin (1.1 grams, 1 mol. plus 100 percent), die'tho'xymethyl acetate (1.62 grams, 1 mol. plus 300 percent), and triethylarnine (0.7 'ml., 1 mol. plus 100 percent) were dissolved in pyridine (15 ml.) and heated under reflux for fifteen minutes. The reaction mixture was stirred with water (100 ml.) and the aqueous portion decanted. The oily residue was extracted with benzene (50 ml.), filtered and boiling ligroin (100 ml.) added and the Benzene boiled "on. The ligroin solution was then chilled, filtered, and the crude dye dried. After two recrystallizations from ligroin, the yield oi purified dye was 0.69 gram (4-5 percent). p. 114-5 C.

14 Example 25. 5-[4-(1-ethy l-2(lH)-naphth0 1,2 thiazolylidene) 3 (2 methyl 3 indolyl) 2 bute'nyl-L rnthyl-Z-thiObz'zrbituTiC aCl d 3" ethyl 2,8 dime'thyl 4',5 benzo 3 indolethiacarbocyanine iodide (1.28 grams, 1 mol.), 1-meth'yl-2- thiobarbituric acid (0.79 gram, 1 mol. plus percent), diethoxymethyl acetate (1.62 grams, 1 mol. plus 300 percent), and triethylamine (0.7 ml., 1 mol. plus 100 percent) were dissolved in pyridine and heated under reflux for fifteen minutes. The crude dye was thrown out of solution by the addition (with stirring) of water (20 ml.). The crude dye was stirred with methyl alcohol (25 ml.) until crystalline and then chilled, filtered, and dried. After two recrystallizations from pyridine and methyl alcohol the yield of pure dye was 0.88 gram ('65 percent). M. P. 322-2" C. dec.

Example 26.3 methyl 4 4 [4 (1 methyl Z(1H)- n'aphth0[1,2]thiazolylidene) 3 (3 pyrr'yl) 2- butenylz'dene1-1 -phenyl-5-pyraz0l0ne 3',6 dimeth'yl 4Z5 benzo 3 pyrrolothiacarbocyanine p toluenesulfon'ate (1.59 grams, 1 mol.), 4- anilinomethylene 3 methyl 1 phenyl 5 pyrazolone (1.38 grams, 1 mol. plus 50 percent), and acetic anhydride (0.4 ml., 1 mol. plus 50 percent) were dissolved inpyridi-ne (20 ml.) and heated to reflux temperature. T-riethylamineCOfl ml., -1 mol. plus 100 percent) was then added with stirring and the reaction mixture allowed to cool slowly to room temperature. The crude dye was thrown out of solution by the addition of water (100 ml.) the water decanted and the residue stirred with methyl alcohol (100 ml.) until crystalline. The mixture was then chilled, filtered, and the crude dye washed with .methyl alcohol and dried. After two recrystallizations 'from pyridine and methyl alcohol, the yield was 0.16 gram (10 percent).

M. P. 220-1 C. dec.

It can be seen from the above examples that in addition to representing an alkyl group, the R2 of Formulas -I and 11 above can represent a hydrogen atom or an aryl group, such as phenyl, o-, m, and p-tolyl, 0-, m-, and p-chlo'rophenyl, etc. (e. -'g. a mononuclear aromatic group of the benzene series).

The following examples will serve to illustrate more fully the manner whereby we prepare the new intermediates represented by Formula III above.

Example 27. 1.,3' 'diethyl 2,5,6 trimeth'yl 3 pyrrdlo'thiacarboeyanine perchlorate (14.6 grams, 1 mol.-H percent excess) and ethyl orthoacetate 24.3 grams, 1 mol.-+200 percent excess) were refluxed in ethyl alcohol (25 ml.) for 4 hours. The reaction mixture was chilled and treated with aqueous :sodium iodide (20 grams in 150 ml.). The solid which separated was filtered oil and discarded. The filtrate was treated with an additional 400 ml. of water and chilled overnight. The product which separated was filtered off, washed with acetone and dried. After conversion to the perchlorate and two recrystallizations from methyl alcohol (and filtered through decolorizing carbon) the yield of pure dye was 4.5 percent; melting point 188190 C.

Analysis.--Calculated for C2cH25CLNzO4S: C, 56.54; H, 5.93. Found: C, 56.9; H, 6.7.

Example 28.] ethyl 2,3,5,6 tetramethyl 3- pyrrolothiacarbocyanine perchlorate N (EH5 Example 29.-] ethyl 2,3,5,6 tetramethyl 4,5' benz0-3-pyrrolothiacarbocyanine iodide CHa C 1,2 dimethylnaphtho[1,2]thiazolium p toluenesulfonate (38.5 grams, 1 mol.), 1-ethyl-2,5-dimethylpyrrole grams, 1 mol. +10 percent excess) and ethyl orthoacetate (24.3 grams, 1 mol+200 percent excess) were refluxed in ethyl alcohol (100 ml.) for three hours. The reaction mixture was then treated with sodium iodide grams) in water (200 ml.), chilled overnight and the solid filtered off and discarded. The solution was treated with an additional 200 ml. of water, chilled, and the aqueous layer decanted. The oily layer was repeatedly washed with water and ether and finally treated with aqueous sodium iodide. The aqueous layer was decanted and the residue stirred with acetone until crystalline and then 1,2-Dimethylnaphtho[1,2]thiazolium p toluenesulfonate (38.5 grams, 1 mol.), 2,5-dimethyl-l-phenylpyrrole (20 grams, 1 mol.+l0 per cent excess) and ethyl orthoacetate (25.0 grams, 1 mol.+200 percent excess) were refluxed in ethyl alcohol for three hours and then treated with sodium iodide (20 grams) in water (400 ml.) and chilled overnight. The aqueous solution was decanted and the residue washed with water and ether and finally stirred with acetone until crystalline. The crude dye was filtered oil and then boiled with water (200 ml.) and filtered hot. The residue was washed with acetone and dried. After two recrystallizations from methyl alcohol (and filtered through decolorizing carbon) the yield of pure dye was 2 percent; M. P. 1923 C. dec.

Example 31.3' ethyl 8 methyl-4,5'-benz0-3-ind0l0- thiacarbocyanine iodide l-ethyl-2-methylnaphtho[1,2]thiazolium p toluenesulfonate (20 grams, 1 mol.), indole (7.5 grams, 1 mol.+20 percent excess) and ethyl orthoacetate (16 grams, 1 mol.-P300 percent excess) were dissolved in acetic acid (25 ml.) and heated under reflux for 30 minutes. The reaction mixture was cooled, poured into water (200 ml.) and stirred with ether (200 ml.). The ether and water were decanted and the crude dye was washed with water, dissolved in ethyl alcohol and converted to the iodide by the addition of sodium iodide (5 grams) in water (50 ml.). The crude iodide was filtered otf, washed with acetone and dried. After two recrystallizations from methyl alcohol, the yield of pure dye was 5%; M. P. 2313 C. dec.

Example 32. 2,3,8-trimethyl-4',5'-benzo-3-ind0lothiacarbocyanine p-toluenesulfonate 1,2 dimethylnaphtho[1,2]thiazolium p toluenesulfonate (19.3 grams, 1 mol.), 2-methylindole (7.5 grams, 1 mol.+20 percent excess) and ethyl orthoacetate (16.2 grams, 1 mol.-H00 percent excess) were refluxed in acetic acid (25 ml.) for 30 minutes. The reaction mixture was cooled and then poured into water (400 ml.) and stirred until crystallization started. The reaction mixture Was then chilled overnight, filtered, and the crude dye stirred with acetone, again filtered, and dried. After two recrystallizations from methyl alcohol, the yield of pure dye was 27 percent; M. P. 2l213 C. dec.

Example 33. 3 ethyl 1,3,8-trimethyl-4,5'-benz0-2- indolothiacarbocyanine iodide 1 ethyl 2 methylnaptho[1,2]thiazolium p toluenesulfonate (20 grams, 1 mol.), 1,3-dimethylindole (7.25 grams, 1 mol.) and ethyl orthoacetate (16.2 grams, 1 mol.-H00 percent excess) were dissolved in acetate acid (25 ml.) and heated rapidly to boiling over a free flame and boiled for thirty seconds. The reaction mixture was then poured into water (200 ml.) and treated with sodium iodide (20 grams). The aqueous portion was decanted and the solid washed with water. The dye was extracted from the quaternary salt with five 200 ml. portions of acetone. The acetone solutions were concentrated to 25 ml., chilled, filtered, and the crude dye dried. After two recrystallizations from methyl alcohol the yield of pure dye was 3 percent; M. P. 209-10 C. dec.

Example 34. 2,3,8 trimethyl-S-indoloxacarbocyanine iodide OH: H

osor-ctm onm 1,2-dimethylnaphtho [1,2] thiazolium p-toluenesulfo nate (14.3 grams, 1 mol.), pyrrole (8 grams, 1 mol.+20 percent excess) and ethyl orthoacetate (16.2 grams, 1

mol.-F300 percent excess) were refluxed in ethylalcohol (50 ml.) for two hours. The reaction mixture was poured into cold water (200 ml.) and stirred until crystallization started. The mixture was then chilled, filtered, and the crude dye washed with water, ether, and acetone. After two recrystallizations from methyl alcohol, the yield was 8 percent; M. P. 2234 C. dec.. I 9

Example 3 6 .3-methy l-2-phenyl-4 ',5 -benz-1 -pyrr0- colothiacarbocyanine p-toluenesulfonate Replace the Z-methylindole of Example 32with a molecularly equivalent amount of 2-phenylpyrrocoline. The dye was obtained as a thick oil, and .was used as such in preparing the dye of Example 6.

Example 37. chl0r0-3-ethyl-2,8-dimethyl-3-ind0l0- thiacarbocyanine p-toluenesulfonate o rgmt-Qcator.

5-chloro-3-ethyl-2-methylbenzothiazolium p-t'oluenesulfonate (19.2 grams, 1 mol.), 2-methy1indole (7.2 grams, 1 mol. plus 10 percent), and ethylorthoacetate (16.2 grams, 1 mol. plus percent) were dissolved in acetic acid (40 ml.) and heated under reflux for thirty minutes. The reaction mixture was poured with stirring into water (500 ml.) and the stirring continued until crystallization started. The mixture was then chilled, filtered, and the crude product stirred with acetone, filtered, and dried. The yield of product was 7.5 grams (28 percent). A one-gram sample of the dye converted to the iodide and twice recrystallized from methyl alcohol yielded 0.55 gram (16 percent). M. P. 244-5 C. dec.

Example 38.3' ethyl 2,8-dimethyl-S-indolothiacarb0- cyanine iodide 3-ethyl 2 methylbenzothiazolium p-toluenesulfonate (17.5 grams, 1 mol.), 2-methylindole (7.2 grams, 1 mol. plus 10 percent), and ethylorthoacetate (16.2 grams, 1 mol. plus 100 percent) were dissolved in acetic acid (40 ml.) and heated under reflux for thirty minutes. The reaction mixture was then poured into water (500 ml.), diethyl ether (400 ml.) added, and the mixture stirred and chilled. The crude product was gravity filtered, the solid dissolved in acetone (500 ml.) and filtered. The acetone solution was evaporated to dryness, the residue washed wtih water, dissolved in methyl alcohol (50 ml.), and converted to the iodide by the addition of sodium iodide (10 grams) in water (50 ml.). The aqueous alcohol was decanted, the residue washed with water, stirred with acetone (100 ml.) until crystalline and then heated to boiling. The mixture was then chilled, filtered, and the crude dye washed with acetone and dried. After two recrystallizations from methyl alcohol, the yield of pure dye was 3.9 grams (17 percent). M. P. 238-9 C. dec.

(ll-CH3 C 3-ethyl-2-methy1benzoxazolium iodide (14.5 grams, 1 mol.), 2-methylindole (7.2 grams, 1 mol. plus 10 percent), and ethylorthoacetate (16.2 grams, 1 mol. plus 100 percent) were dissolved in acetic acid (20 ml.) and heated under reflux for thirty minutes. The reaction mixture was poured into cold water (400 ml.) with stirring and then diethyl ether (200 ml.) was added. The mixture was then chilled, filtered, and the crude product stirred with acetone (50 ml.). The crude dye was filtered ofl, washed with acetone, and dried. The yield of pure dye after two recrystallizations from methyl alcohol was 3.3 grams (15 percent). M. P. 248-9 C. dec.

19 Example 40.-3 ethyl 8-methyZ-3-ind0l0thiacarb0cyanine iodide 3 ethyl 2-methylbenzothiazolium p-toluenesulfonate (34.9 grams, 1 mol.), indole (11.7 grams, 1 mol.), and ethylorthoacetate (24.3 grams, 1 mol. plus 50 percent) were dissolved in acetic acid (50 ml) and heated under reflux for thirty minutes. The reaction mixture was cooled, poured into water (500 ml.) containing sodium iodide (20 grams) and then chilled overnight. The aqueous solution was decanted, the residue stirred with acetone, chilled, and filtered. The crude product was washed with a little acetone and dried. After two recrystallizations from methyl alcohol, the yield of pure dye was 7.1 grams (16 percent). M. P. 249-50 C. dec.

Example 41.3-ethyl-2,8-dimthyl-4',5'-benz0-3-ind0lolhiacar'bocyanine iodide l-ethyl-Z-methylnaphtho [1,2] thiazolium p-toluenesulfonate (20 grams, 1 mol.), Z-methylindole (7.8 grams, 1 mol. plus 20 percent), and ethylorthoacetate (16.2 grams, 1 mol. plus 100 percent) were dissolved in acetic acid (25 ml.) and heated under reflux for thirty minutes. The reaction mixture was poured into water (200 ml.) containing sodium iodide grams) and then diethyl ether (200 ml.) was added with stirring. The mixture was chilled overnight, filtered, and the crude product stirred with acetone (50 ml.), filtered, and dried. The yield of pure dye aftertwo recrystallizations from methyl alcohol was 2.02 grams (8 percent). M. 'P. 221-2" C. dec.

We have found that our new dyes spectrally sensitized photographic silver halide emulsions when incorporated therein. The dyes are especially useful for extending the spectral sensitivity of the customarily employed gelatinosilver-chloride, gelatino-silver-chlorobromide, gelatinosilver-bromide and gelatino-silver-bormiodide developingout emulsions. In the foregoing "examples, the extent to which gelatino-silver bromiodide developing-out emulsions can be sensitizedas Well as the point of maximum sensitivity are pointed out in connection with the dye of each example. To prepare emulsions sensitized with one or more of our new dyes, it is only necessary to disperse the dye or dyes in the emulsions. The methods of incorporating dyes in emulsions are simple and are known to those skilled in the art. In practice, it is convenient to add the dyes to the emulsions in 'the form of a solution in an appropriate solvent. Methanol has proved satisfactory as a solvent formost of our'new dyes. Where the dyes are quite insoluble in methyl alcohol, for instance, a mixture'of methanol and pyridine is advantageously employed as a solvent. The dyes are advantageously incorporated in the finished, washed emulsions and should be uniformly distributed throughout the emulsion.

The concentration of the dyes in the emulsions can vary widely, e. g. from S'to 100 mg. per liter of flowable ernulsion. The concentration of the dyes will vary according 7 to the type of emulsion and according to the effect desired. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art, upon making the ordinary tests and observations customarily used in the art of emulsion making. To prepare a 'gelatino-silver-halide emulsion sensitized with one or more of our new dyes, the following procedure is satisfactory:

A quantity of dye is dissolved in methyl alcohol (or a mixture of methyl alcohol and pyridine) and a volume of this solution, which may be diluted with water, containing from 5 to mg. of dye, is slowly added to about 1000 cc. of gelatino-silver-halide emulsion, with stirring. Stirring is continued until the dye is thoroughly dispersed in the emulsion.

With most of our dyes, from 10 to 20 mg. of dye per liter of gelatino-silver-bromide or bromiodide emulsion (containing about 40 g. of silver halide) sufiices to produce the maximum sensitizing eifect. With the finer grain emulsions, somewhat larger concentration of dye may be needed to produce the maximum sensitizing effect.

The above statements are only illustrative, as it will be apparent that the dyes can be incorporated in photographic 'emulsions by any of the other methods customarily employed in the art, e. g. by bathing a plate or film upon which an emulsion is coated in a solution of the dye in an appropriate solvent. However, bathing methods are ordinarily not to be preferred. Emulsions sensitized with the dyes can be coated on suitable supports, such as glass, cellulose derivative film, resin film or paper in the usual manner.

When preparing intermediates as described in Example 35 above, wherein unsubstituted pyrrole is employed, the condensation might result in the formation of 3,6-dimethyl-4',5-benzo-2-pyrrolothiacarbocyanine p toluenesulfonate, although present evidence favors the compound depicted in Example 35.

As shown in Examples 24 and 25, the polymethine dyes represented by Formula II above can advantageously be prepared by condensing a compound selected from those represented by Formula III with a dialkoxymethyl acetate, e. g. diethoxymethyl acetate, etc., and a 'ketomethylene compound selected from those represented by the following general formula:

wherein Q has the values given above. The condensations can advantageously be carried out in the presence of a basic condensing agent, such as those set forth above for the condensation of the compounds of Formula III with those of Formula IV or V. Triethylamine has been found to be particularly efiicacious in accelerating the desired condensation. Also, the condensation can be carried out in the presence of an inert diluent, such as pyridine, the aliphatic alcohols (e. g. ethanol, n-propanol, etc.), etc.

What we claim as our invention and desire secured by Letters Patent of the United States is:

1. A polymethine dye selected from those represented wherein R represents an alkyl group containing from 1 to 5 carbon atoms, R2 represents a member selected from the group consisting of a hydrogen atom, an alkyl group containing from 1 to 2 carbon atoms, and a monocyclic aryl group ofthe benzene series, R3 represents a member 5 selected from the group consisting of a hydrogen atom,

an alkyl group containing from 1 to 12 carbon atoms,

N H H wherein R and R each represents a lower alkyl group.

3. The polymethine dyes represented by the following general formula:

wherein R and R each represents a lower alkyl group. 4. The polymethine dyes represented by the following general formula:

O=C----N-CaH wherein R represents a lower alkyl group.

5. The polymethine dyes represented by the following general formula:

R HaC-C R HzC-C wherein R and R each represents a lower alkyl group.

6. The polymethine dyes represented by the following general formula: A

O=CHC=CHOH=C /c=s wherein R and R each represents a lower alkyl group.

7. The polymethine dye having the following formula:

0 s -NC1Hr l CH CH3 g 8. The polymethine dye having the following formula:

O=ONG2H5 9. The polymethine dye having the following formula:

10. The polymethine dye having the following formula:

C2H5 HaC-C 11. The polymethine dye having the following formula:

No references cited. 

1. A POLYMETHINE DYE SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 